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'A ~ <br />R rcnartl D Lamm <br />Governor <br />III IIIIIIIIIIIIIIII <br />DEPARTMENT OF NATURAL RESOURCES 999 <br />D Moore Pascoe. Exec un ve Drte G Cr <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SHEITON Director <br />Afa rch 17, 1982 <br />TO: Carol Russel l Qp,~}.-~~ .._. <br />~~%"`~-_ <br />FROFf: Jim Pendleton }<*^'~ <br />RE: GEC's Regues['foz ' / z'oval of Auger Mining <br />Pursuant to your request, I have reviewed that portion of GEC'lfinerals, int.'s <br />supplemental submittals dealing [pith proposals for auger mining. I fonward <br />the foZloewiny comments for your consideration. <br />The applicant has arr~nded the augering proposal, pursuant to comments contained <br />within our earlier adequacy reviews. GEC proposes to conduct augering <br />operations at the exposed highwwalls created during the process of their <br />contour stripping mine plan. The company proposes to penetrate a~prcximately <br />150 feet beyond the exposed coal seam high[wa11. The configuration of the <br />area to be mined is ,such that, as the operator observes; "Access to these <br />small amounts of remaining reserves would be difficult and impractical by any <br />other method of mining." I concur with that opinion. <br />The applicant includes discussion of appropriate techniques to avoid hazards <br />due to highwall spaZling, entry into potentially hazardous existing under- <br />ground work in g5 anal appropriate machinery and construction hazards, In order <br />to avoid the potential of highwall collapse, the applicant proposes to utilize <br />a minimum 8" rib thickness between auger holes. Normal guidelines, as <br />presented in U.S. Bureau of Plines Open File Report 108-7G, entitled "Technology <br />of Auger l4inina" (October, 1975), suggest that a rib thic}:Hess equivalent to <br />1/6 of the mined seam thickness should be retained between auger holes. <br />Stratigraphic data presented by GEC [within the permit application indicates <br />that seam No. 2 reaches a reported maximum thickness of 5 feet. In areas rihere <br />seam thickness exceeds ?8" the proposed 8" rib may not be adeouate, In <br />areas of seam thickness oreater than ?8", I recommend that [ve require the <br />applicant to maintain a rib thickness equivalent to 1/6 that of the actual <br />seam thickness. <br />The applicant proposes to prevent possible effluent water quality and backfill <br />stability problems by sealing any auger holes encountering water [with <br />impermeable overburden materials immediately folloc.~ing completion of the augering <br />operation. Sufficient clay materials are available from the overburden <br />materials encountered at the mine site. <br />r~3 ,^ente:~n'nl E~ .: r 1a [3 Sh?rman S!reet Denver. Colorado 80203 Tel. (303) 2° ~-3667 <br />